Transportation of fertilized eggs and yolk-sac larvae of hilsa shad, Tenualosa ilisha (Hamilton, 1822) in different transportation systems

Abstract

Hilsa shad, Tenualosa ilisha has received much attention for their conservation through culture. Transportation mechanism of eggs and larvae is one of the major bottlenecks of hilsa culture. The present study aims to find out the best transporting system, stocking density (SD) and early life stages that record maximum survival after transport needed to facilitate hilsa culture. Eggs and yolk-sac larvae (1-h, 10-h and 6-days old) of hilsa, Tenualosa ilisha were transported in different systems (CAFPB, closed air filled polyethylene bag; COFPB, closed oxygen filled polyethylene bag; CAFBPJ, closed air filled big plastic jar; OAH, open aluminium hundi; CAFSPJ, closed air filled small plastic jar; CAFMPJ, closed air filled medium plastic jar) and SD. Egg survival in CAFPB and COFPB was 32.83–84% depending on the transporting system and SD. In CAFPB and COFPB, egg survival was negatively correlated (P < 0.01) with SD. At all SD (100, 300, 500, 700 and 1000 nos. L−1), COFPB showed higher egg survival than in CAFPB. At 100 nos. L−1, egg survival in CAFPB and COFPB was higher (P < 0.05) than that of 300, 700 and 1000 nos. L−1. The best option for egg transportation was COFPB with 100 L−1 SD. The survival of 1-h old yolk-sac larvae at 1000 nos. L−1 was 97.96–99.32% in different transporting systems. The survival of larvae was higher (P < 0.05) in COFPB than that of CAFPB and CAFBPJ and also in CAFPB than that of CAFBPJ. The 10-h old yolk-sac larvae at 100 nos. L−1 in different closed systems (CAFPB, CAFSPJ and CAFMPJ) exhibited significantly (P < 0.05) higher survival (94.44–98%) than that in open system (OAH) with 60.1% survival being unsuitable for transportation. The survival of 6-days old yolk-sac larvae at 50, 100, 200, 300 and 400 nos. L−1 varied between 97 and 99.7% during 2 h of transportation in COFPB. Based on the present study, it is concluded that hilsa eggs and larvae could be transported in closed polyethylene bags filled with oxygen or atmospheric air, the former being the best. Among the eggs and yolk-sac larvae (1-h, 10-h and 6-days old), survival of larvae is much higher (94.44–99.7%) than that of the egg (32.83–84%). The most suitable stage for transportation is 1-h old larvae as they could be transported at high stocking density (1000 nos. L−1) with high survival (97.96–99.32%) in different closed transporting systems (CAFBPJ, CAFPB and COFPB).